For your own ease of being able to comfortably pass the ATPL exams, I would recommend Maths and Physics; the other two are up to you. I would personally recommend English, although subjects like Business Studies would just stand you in stead for the future.
If you're planning on paying for all your own training, I would also recommend subjects that would get you another job/career on which to fall back if you are not successful in getting into aviation.
Cheers
Whirls